1. Field of the Invention
The present invention relates to an apparatus and a method for effecting cutting, valve insertion and anticorrosive works on an existing pipe without a need to interrupt the supply of a fluid therethrough.
2. Description of the Related Arts
Up until now, a fluid supply interruption free valve insertion method is widely known in which a water flow through a pipeline can be stopped by forming an opening in an existing pipe without interruption of the water supply and inserting a gate through the opening to thereby allow a stopping of the water flow through the pipeline (U.S. Pat. Nos. 3,948,282, 4,516,598, 5,611,365 and 5,732,728, U.S. patent application Ser. No. 09/195,601 (Japan Patent Laid-open Pub. Nos. Hei11-287385 and 2000-179779)).
In such a method, the water flow is stopped by a gate after the valve insertion in order to perform the objective work such as a modification of piping.
The method disclosed in U.S. Pat. No. 5,732,728 includes enabling a gate passage aperture for inserting the gate therethrough to be opened or closed by sealing means and inserting a cutting tool through the gate passage aperture to cut the existing pipe. After the completion of the cutting, the massive sealing means are opened or closed to withdraw the cutting tool and thereafter insert the gate.
In this conventional method, the cutting tool is not to be withdrawn unless the massive sealing means are opened and closed. It is also required to deeply dig the earth beneath the existing pipe due to the necessity to cut the existing pipe over the entire circumference.
FIG. 44 is a transverse sectional view of an apparatus for use in the method disclosed in Japan Patent Laid-open Pub. No. Hei11-287385.
As shown, a seal-up housing 500 consists of a lower housing part 501 and an upper housing part 502. The lower housing part 501 is mounted with a drill 505 having a cutting tool 504. The upper housing part 502 is blocked off by a block-off plate. In this conventional method, a cut groove is first formed over the entire circumference of the existing pipe 1 by means of the cutting tool 504. Then, after the completion of the cutting, the block-off plate 503 is withdrawn and thereafter a gate not shown is mounted on the upper housing part 502.
This conventional method needs a deep dig of the earth beneath the existing pipe 1 due to the attachment of the drill 505 to the lower housing part 501.
FIG. 45 is a transverse sectional view showing the state where the valve insertion is complete by use of the method disclosed in Japan Patent Laid-open Pub. No. 2000-179779.
As shown, a seal-up housing 600 consists of a first housing part 601 and a second housing part 602. The first housing part 601 is provided with an aperture 603 for inserting a cutting tool not shown therethrough and with an operation valve 604. The first housing part 601 is further provided with a gate passage aperture 606 through which a gate 605 passes upon the opening or closing thereof.
In this conventional method, the seal-up housing 600 is turned through substantially half the circumference so as to allow the cutting tool to form a cut groove 607 in the existing pipe 1 by a half round. Then, after the withdrawal of the cutting tool, the operation valve 604 is closed.
This conventional method posed quite a few problems from the above description.
Due to the necessity to turn the massive gate 605 and the seal-up housing 600, the increased nominal diameter (bore) of the existing pipe 1 results in a larger-scale unit for turning the seal-up housing 600 around the existing pipe 1.
After the completion of the objective work such as the modification of piping, it may possibly be difficult to withdraw the gate 605 or it may take a lot of time and labor for the withdrawal. For this reason, this method is not suited for the case where the existing pipe 1 is buried at a shallow depth.
Due to its formation by drilling or cutting, the cut groove (opening) of the above conventional methods has not undergone sufficient corrosion-resistant measures.
In case of less than 25 mm diameter piping water supply work, a hollow copper bush is caulked and inserted into such an opening to thereby take corrosion-resistant measures.
Due to the need for the step of spreading and caulking the bush, however, such corrosion resistant measures could not be applied to the case of larger bore as in the water distribution work (more than 50 mm diameter). Furthermore, the method may become complicated since the opening is not hermetically closed.
In order to solve the above problems, the anti corrosive member of the present invention is one for use in a fluid supply interruption free work hermetically closing a circular or grooved opening formed in an existing pipe through about 180 degrees or through the angular range slightly smaller than 180 degrees in the circumferential direction of the existing pipe. The anticorrosive member has a shape corresponding to the opening but is incapable of impeding the flow of water through the interior of the existing pipe (i.e., the anti corrosive member does not act as a valve body). The anticorrosive member comprises a pressure contact portion made of elastomer coming into pressure contact with a cut surface of the opening over substantially the entire periphery; and a rigid portion integrally formed with the pressure contact portion and having a rigidity enough to resist the water pressure acting on the opening.
The circular opening may be formed by means of a known hole saw. The grooved opening may be formed by an end mill or a fraise.
In the present invention, the xe2x80x9crigid portionxe2x80x9d is typically made of ductile cast iron, steel, stainless steel, etc.
Such an anticorrosive member is enclosed in the seal-up housing together with the following gate to make up an anticorrosive member inserting apparatus.
In this case, the gate enters the interior of the existing pipe by way of the opening to cut off the flow of water through the interior of the existing pipe. On the other hand, the seal-up housing comprises a plurality of housing parts segmented in the circumferential direction of the existing pipe and encloses the anticorrosive member and the gate.
The fluid supply interruption free method of the present invention uses the anticorrosive member inserting apparatus, etc., and comprises an enclosing step, an opening formation step, a water stop step, a removal step and a hermetically closing step which will be described hereinbelow.
The enclosing step includes hermetically enclosing a part of an existing pipe by the seal-up housing.
The opening formation step includes forming a circular or grooved opening in the existing pipe within the seal-up housing, the opening extending through about 180 degrees or through the angular range slightly smaller than 180 degrees.
The water stop step includes stopping the flow of water through the interior of the existing pipe by allowing a gate for stopping the flow of water through the interior of the existing pipe to enter the interior of the existing pipe through the opening.
The removal step includes removing the gate from the opening.
The hermetically closing step includes fitting the anticorrosive member into the opening, the anticorrosive member including a pressure contact portion made of elastomer coming into pressure contact with a cut surface of the opening over substantially the entire periphery, and a rigid portion integrally formed with the pressure contact portion and having a rigidity enough to resist the water pressure acting on the opening.
By use of such a fluid supply interruption free method, a piping structure of the present invention is obtained.
More specifically, the piping structure of the present invention comprises an existing pipe and an anticorrosive member. The existing pipe has an outer peripheral surface formed with a cut opening, the opening extending through about 180 degrees or through the angular range slightly less than 180 degrees in the circumferential direction of the existing pipe. The anticorrosive member has a shape corresponding to the opening and is incapable of impeding the flow of water through the interior of the existing pipe. The anticorrosive member includes a pressure contact portion made of elastomer coming into pressure contact with a cut surface of the opening over substantially the entire periphery, and a rigid portion integrally formed with the pressure contact portion and having a rigidity enough to resist the water pressure acting on the opening.
The anticorrosive member may remain stored in the seal-up housing in such a manner that it is fixedly placed therein, but instead the seal-up housing may be removed if the anticorrosive member is fastened to the existing pipe by means of a band.
As used herein, xe2x80x9celastomerxe2x80x9d can be gel, unbridged resin, resin sponge, etc., other than rubber.
According to the present invention, the copper bush need not be expanded, making it applicable to any large-diameter distribution work. Furthermore, by virtue of the anticorrosive member provided with the rigid portion to hermetically close the opening, it will become easy to mount the plate flange for example after the hermetic closing.
In order to solve the other problem, the fluid supply interruption free cutting apparatus of the present invention comprises a seal-up housing and a drill. The seal-up housing comprises a plurality of housing parts segmented in the circumferential direction of the existing pipe, the seal-up housing hermetically enclosing a part of the existing pipe and the anticorrosive member. The drill has a milling cutting tool that is revolved by a motor.
The seal-up housing has a structure suited to turn around the existing pipe in the circumferential direction thereof.
A first housing part which is one of the housing parts has integrally formed a cutting tool insertion aperture and a gate passage aperture. The cutting tool insertion aperture allows the insertion of the milling cutting tool. The gate passage aperture allows the passage of the gate that is inserted therein for the purpose of stopping the flow of a fluid through the interior of the existing pipe after cutting of the existing pipe.
The fluid supply interruption free cutting apparatus is provided with a first operation valve arranged to open or close the gate passage aperture and with a second operation valve arranged to open or close the cutting tool insertion aperture.
The fluid supply interruption free cutting method of the present invention is effected by use of the fluid supply interruption free cutting apparatus and comprises an assembling step, an infeed step, a feed step and a tool removal step which follow.
The assembling step includes hermetically enclosing a part of the existing pipe by means of the seal-up housing and allowing the cutting tool to enter the interior of the cutting tool insertion aperture with the second operation valve opened.
The infeed step includes feeding the cutting tool inwardly in the radial direction of the existing pipe while simultaneously revolving the cutting tool to impart thereto a cutting motion for cutting the existing pipe by revolutions of the cutting tool.
The feed step includes turning the seal-up housing around the existing pipe in the circumferential direction thereof while continuing the cutting motion. This turning causes a rotation of the cutting tool in the circumferential direction of the existing pipe and thus a feed motion of the cutting tool. This feed motion allows the cutting tool to cut the existing pipe over the range of substantially the half circumference in the circumferential direction without creating any cut-off sections. This cutting results in a formation of a cut groove that extends over the range of substantially the half circumference in the circumferential direction of the existing pipe.
The tool removal step includes removing the cutting tool from the seal-up housing after the completion of the cutting and thereafter closing the second operation valve.
On the other hand, the fluid supply interruption free valve inserting apparatus of the present invention comprises a seal-up housing and a gate.
The seal-up housing comprises a plurality of housing parts segmented in the circumferential direction of an existing pipe, the seal-up housing hermetically encloses a part of the existing pipe. The gate is arranged to be inserted for cutting off the flow of a fluid through the interior of the existing pipe after cutting of the existing pipe.
A first housing part of the seal-up housing has integrally formed a cutting tool insertion aperture through which the milling cutting tool is inserted and a gate passage aperture through which the gate passes.
In this inserting apparatus, the inserting apparatus is provided with a first operation valve arranged to open or close the gate passage aperture and with a storage casing which stores the gate while the gate is opened.
The storage casing and the seal-up housing are each provided with a flange adapted to join the storage casing storing the gate to the seal-up housing with the first operation valve closed.
The fluid supply interruption free valve inserting method is effected by using the fluid supply interruption free valve inserting apparatus and comprises an assembling step, an infeed step, a feed step, a tool removal step and a gate mounting step which follow.
The assembling step includes hermetically enclosing a part of the existing pipe by means of the seal-up housing and allowing the cutting tool to enter the interior of the cutting tool insertion aperture with a second operation valve opened, the second operation valve arranged to open or close the cutting tool insertion aperture.
The infeed step includes feeding the cutting tool inwardly in the radial direction of the existing pipe while simultaneously revolving the cutting tool to impart thereto a cutting motion for cutting the existing pipe by revolutions of the cutting tool.
The feed step includes turning the seal-up housing around the existing pipe in the circumferential direction thereof while continuing the cutting motion. This turning causes a rotation of the cutting tool in the circumferential direction of the existing pipe and thus a feed motion of the cutting tool. This feed motion allows the cutting tool to cut the existing pipe over the range of substantially the half circumference in the circumferential direction without creating any cut-off sections. This cutting results in a formation of a cut groove that extends over the range of substantially the half circumference in the circumferential direction of the existing pipe.
The tool removal step includes removing the cutting tool from the seal-up housing after the completion of the cutting and thereafter closing the second operation valve.
The gate mounting step including joining the storage casing storing the gate therein to the seal-up housing with the first operation valve closed after the formation of the cut groove.
According to the apparatus and method of the present invention, a desired cut groove can be formed by allowing the seal-up housing to turn through a half-round around the existing pipe. Attachment of the cutting tool and the gate to the first housing part will eliminate the necessity to dig the earth beneath the existing pipe to a large extent.
Provision of the first and second operation valves facilitates the removal of the cutting tool.
During the cutting, the seal-up housing is turned around the existing pipe without any massive gate so that the seal-up housing can turn with a small magnitude force.
After the stopping the water flow in the existing pipeline by the gate inserted through release of the first operation valve, the gate is retracted in the storage casing. Then, after the closing of the first operation valve, the gate and the storage casing is withdrawn. This eliminates any elements that project to a large extent above the existing pipe, enabling the work to be effected on the existing pipe which has been buried at a shallow depth.
In the present invention, xe2x80x9cexisting pipexe2x80x9d refers to a pipe through which flows a liquid such as water or oil, and is typically often buried in the ground.
xe2x80x9cSeal-upxe2x80x9d does not mean perfectly hermetically sealing, but means that a watertightness is kept to such a degree as to allow a suspension-free work. Therefore, xe2x80x9cseal-up housingxe2x80x9d refers to a housing which has pressure resistance properties capable of resisting the pressure of liquid flowing through the interior of the existing pipe and which has certain water stop properties.
xe2x80x9cHermetically enclosexe2x80x9d means sealing something to such an extent as not to cause any inconvenience to cut or other works. For example, the seal-up housing may be provided with a drain opening arranged to be opened during the cut to drain cutting chips together with water therethrough.
xe2x80x9cCutting toolxe2x80x9d for use in this method is preferably a milling tool having a plurality of cutting edges at its tip surface and peripheral surfaces.
In case of cutting an existing pipe having a mortar lining formed along its inner surfaces, it is preferred to use a cutting tool provided with a multiplicity of chips made of a hard metal or a cutting tool having cutting edges made of diamond particles.
As used herein, xe2x80x9ccutxe2x80x9d means cutting a part of the pipe wall by turning the cutting edges. xe2x80x9cCutting motionxe2x80x9d means turning the cutting edges, whereas xe2x80x9cfeed motionxe2x80x9d means moving the cutting tool to positions allowing fresh portions of the pipe wall to be cut in succession by the cutting tool.